Wireless communication networks may be used for numerous applications including tactical military and commercial applications. Tactical military and commercial application require self-organizing, wireless networks that can operate in dynamic environments and provide peer-to-peer, multi-hop, multi-media communications. A structured wireless channel access scheme such as Time Division Multiple Access (TDMA) may be used in an ad hoc wireless network. TDMA is a channel access technique in which a frequency channel is divided into time slots and each time slot is assigned to a user. Accordingly, multiple transmissions may be supported on a single frequency channel. Multiple channels may be used in an ad hoc wireless network to allow simultaneous communication of neighboring nodes. A multi-channel (or multi-frequency) TDMA access scheme such as Orthogonal Domain Multiple Access (ODMA) may be utilized to support multiple channels.
Nodes in a wireless communication network (e.g., a commercial wireless network, a military wireless network, etc.) are configured to transmit and receive data using various communication protocols. During transmission and reception of packets of data, errors may occur, for example, a packet of data may be lost or data may be corrupted. Various protocols have been developed to handle communication errors and provide end to end reliability of data. For example, the Transmission Control Protocol (TCP) is the reliable transport protocol within the TCP/IP protocol. TCP is used to provide end to end reliability at higher layers. Wireless networks, however, have very limited bandwidth and TCP does not scale well in highly congested and error prone wireless networks. In addition, the overhead associated with TCP may be very high. Various protocols have been proposed that provide TCP like behavior at the Link Layer but these protocols do not scale well and do not dynamically adjust to changing wireless network conditions. In addition, these protocols may not provide priority to packets that are considered high priority and may have latency issues.
A standard method of handling communications errors is the Automatic Retransmit Request (ARQ) protocol. ARQ is an error control method in which the receiver node detects transmission errors in a message and automatically requests a retransmission from the transmitter. Three types of standard ARQ are Stop-and-Wait, Go-Back-N and Selective Repeat. In the Link Layer, these ARQ methods are implemented at the Logical Link Control (LLC) and are Link Layer frame dependent. A problem may occur in this implementation, however, when the Link Layer Protocol Data Unit (LPDU) is fragmented (e.g., a cell) to meet the Maximum Transmission Unit (MTU) of the media (e.g., a TDMA slot). Another problem with standard ARQ methods is that if cells are routed independently and cell(s) are lost, the standard ARQ methods have potentially large delays at the receiving peer LLC. Standard ARQ methods also may not account for duplicated cells that need to be deleted on a hop-by-hop basis (when using cell relay) to ensure that bandwidth is not wasted in an error prone congested network. Standard ARQ methods also may not take into consideration effects of the Forward Error Correction (FEC) block size on the ARQ. In addition, standard ARQ methods typically treat all transmission equally and do not provide priority based retransmissions.
Accordingly, there is a need to provide scalable end-to-end reliable transmissions in a wireless network by providing a priority based adaptive ARQ. There is also a need for providing an ARQ that dynamically adjusts to wireless network conditions by adjusting the retransmission timer and timeouts. There is also a need to provide an ARQ that dynamically adjusts the Acknowledgement Code (ACK)/Negative Acknowledgement Code (NAK) granularity based on wireless transmission reliability. Further, there is a need to provide a scalable mobile adaptive reliable ToS based ARQ.
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.